Laminated products, i.e., products formed from layers of materials interconnected by mounting or other laminating technique, are utilized for a number of reasons. First, laminated products allow manufacturers to advantageously combine materials having different attributes or properties in a single product. For example, a laminated product such as a display device can include a backing formed from an inexpensive or sturdy material attached to a front panel formed from material which has the desired appearance or is easily processed. In addition, laminated products are useful where it is desirable to provide the product with a pull-out flap, window, pocket or the like. Examples of such devices include paperboard display devices having a fold-out easel such that the devices are self-standing, cardboard game pieces with pop-out windows which a contestant can remove to reveal prize information, packages provided with a flap which pulls out to form or provide access to a spout for pouring the package contents, and products which include a pocket, for example, to receive the flap of a paper pad or other items.
In forming a laminated product, the layers of the product are commonly attached using an adhesive. However, in some cases, adhesives are believed to be responsible for subsequent undesired warping, curling or bending of the laminated product. In particular, the adhesive can be partially absorbed into one or both of the layers being bonded causing the layer(s) to swell or otherwise become dimensionally unstable. Warping, curling or bending can occur in the finished product particularly where the layers are unequally affected by adhesive absorption, e.g., due to differences in porosity, fiber length or orientation, or other factors.
In addition, the process for producing laminated products incorporating a window, flap, pocket or the like is typically relatively complex, time-consuming and expensive. The case of paperboard display devices having a fold-out easel is illustrative. Such devices are commonly constructed from a front panel and an easel assembly which are adhesively interconnected, e.g., by applying glue therebetween, to form the display device. Often, the front panel is formed from a thick sheet of corrugated cardboard and has a forwardly facing display surface which can be formed from a separate label which is glued to the front panel. The easel assembly typically is formed from thick corrugated cardboard and includes flaps which can be deployed by folding the flaps rearwardly to provide support. As is readily appreciated, it is desirable to avoid adhesive attachment of the flap to adjacent portions of the display device so that the flaps can be easily deployed.
One known process for producing such paperboard display devices involves applying an adhesive across the extent of the interface between front panel and the easel assembly except for that portion of the interface where the easel flaps are located. Accordingly, glue can be applied to portions of the front panel or easel assembly around the flaps in a pattern which complements the shape of the flaps. Because glues are often tacky and highly viscous and therefore are poorly suited for certain high speed application techniques such as lithographic printing, the glue is commonly applied by silk-screening or a similar relatively slow and labor intensive process, thereby limiting production output and increasing production costs. Silk screening processes also result in usage of relatively large quantities of glue, further increasing production costs.
Manually coating panels with an adhesive by a process such as described above typically results in coating rates below about 120 panels per labor hour. Machines have been developed to mechanize the above-described process, including a machine known as the Automatan manufactured by Mirus Co. However, such machines are typically relatively expensive and are usually dedicated to particular coating applications, thereby increasing costs.
In addition, the resulting display device, including the front panel and the attached easel assembly, typically is not of uniform thickness due to the increased thickness of the device where the easel is attached. As a result, the display devices are clumsy to handle, take up a greater space during shipping and storage thereby increasing costs and can shift or fall during shipping or storage thereby creating a hazard. In this regard, shipping costs for such display devices can be up to $40,000 or more per 100,000 pieces. Moreover, a relatively large amount of corrugated cardboard is used in constructing such display devices thereby further increasing costs.